Laminates



g- 1961 R. D. LOWRY ,ET AL 2,997,170

LAMINATES Filed Dec. 16, 1959 FIG]. 16.2. F1613.

INVENTORS ROBERT D. LOWRY JOHN W.HARRISON BY My), 9901f? ATTORNEY United States Patent 2,997,170 LAMINATES Robert D. Lowry and John W. Harrison, Winchester, Mass., assignors to W. R. Grace & Co., Cambridge,

5., a corporation of Connecticut Filed Dec. 16, 1959, Ser. No. 860,040 1 Claim. (Cl. 20665) This invention relates to a new laminate and method of making same.

More particularly the invention relates to the use of a film of an irradiated polyethylene or irradiated polypropylene, i.e. an irradiated polymer of an olefin having 2 to 3 carbon atoms as a laminant for use as a surface protectant and decorative layer for materials such as paper, wood, metal, etc. to provide improved water and chemical resistance, scuff resistance, and high gloss.

An object of this invention, therefore, is to provide such an improved laminate.

Another object is to provide improved containers-having wide commercial adaptation, which containers are made from the above-mentioned new laminate material.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention wil become apparent to those skilled in the art from this detailed description.

Many articles like phonographrecords, stockings, candy, etc. are packaged in a relatively thin cardboard box or envelope. It has been found that such packages can be rendered tamper proof, dust proof, moisture resistant and provided with a high gloss, scufi resistant covering for improved shipping and handling characteristics by manufacturing the box or envelope from laminate stock which has been preprinted and had a surface lamination of .a film such as irradiated polyethylene or irradiated polypropylene applied so as to have an excess of film extending beyond the cardboard edge in the area which will become the final closure.

It has been found possible to bond to paper, wood, and metal, a film of irradiated polyethylene or irradiated polypropylene with adhesives and to paper and metal with combined heat and pressure using care to restrict possible film shrinkage during cooling when biaxially oriented film is employed.

In a bonding operation, it is necessary to avoid bubbles and air pockets while laminating, or even the inclusion of a laminating agent which can release gas to cause similar protuberances in the plastic material.

Adaptations of this invention include laminations of irradiated polyethylene or polypropylene to covers of paper-backed books and packaging board, lamination to wood for table tops, etc., protection of metals from abrasion and chemical attack during manufacture and use. The irradiated polyethylene or polypropylene can be unoriented or monoaxially oriented. However, when advantage is to be taken of shrink characteristics it should be biaxially oriented.

In all of the specific examples there was employed Alathon 14 polyethylene which had been irradiated to an extent of 12x10 rad and had been biaxially oriented as disclosed in Colombian Patent 8,767 of April 22, 1959, to an extent of 350% longitudinally and 350% laterally and had a shrink energy of 250 psi. at 96 C.

Example 1 A film of irradiated polyethylene film 1 mil thick was laminated by use of a clear adhesive, e.g. an epoxy resin ICC such as bisphenol A-epichlorohydrin to an ordinary filing card. A generous amount of black ink was spilled upon the laminated card and it immediately formed a small globule which was very easily wiped off without leaving a trace of its presence.

Example 2 'A second filing card laminated as that in Example 1 was heavily marked with a wax pencil. Rather than adhering and marring the film surface, the wax markings were found to be easily removable by merely wiping with a cellulose tissue.

Example 3 To test the abrasion resistance of the laminated film of Example 1, it was subjected to moderate hard pressure erasure strokes using a fiber glass typewriter eraser. It was found that at least fourteen strokes were needed to even slightly skin back the film.

As illustrative of the adaptability of this invention to the manufacture of containers or closures the following example was performed.

Example 4 An irradiated polyethylene film 1 mil thick was laminated by use of a clear adhesive i.e. bisphenol A-epichlorohydrin resin to a conventional printed record envelope in a manner such that a inch flap extended from either face past the opening of the cardboard envelope. After insertion of the record, the flaps were heat sealed using an impulse sealer which seals and cuts simultaneously so that the sealed and cut edge was about .4 inch from it is also possible to use an overwrap closure and an ordinary heat seal on this end.

If a box, in fact, is used and backings or tucked end flaps are desired, the adhesive could be omitted from that area during the combining operation. Furthermore, certain types of boxes can have the seal at both ends if desired.

FIIGURE 1 is a perspective view of a blank of materia FIGURE 2 is a perspective view of a blank coated with an adhesive;

FIGURE 3 is a perspective view of a laminate material made in accordance with this invention;

FIGURE 4 is a perspective view within a fihn wrapper illustrating a step in the method embodying the invention;

FIGURE 5 is a perspective view of a complete article made in accordance with the process embodying the invention;

FIGURE 6 is a perspective view of a stack of complete articles made in accordance with this invention;

FIGURE 7 is a perspective view of a complete package of a piece of confectionery wrapped in accordance with this invention, and

FIGURE 8 is a perspective View of a stack of complete articles made in accordance with this invention.

Referring in detail to the drawings, FIGURES 1-3 show an ordinary blank of paper, wood or metal 10 coated with an adhesive 12.

The blank 10 can be, for example, a filing card, a playing card, a metal plate or a wooden plaque, etc.

3 4 Laminated to the blank 10 by the adhesive 12' is a, film rads. The irradiation can be accomplished in convenof irradiated polyethylene 14. tional fashion, e.g., by the use of a high voltage resonant FIGURES 4, 5 and 6-are perspective i hi bill transformer, such as the 2,000,000 volt General Electric tr'ate a record envelope 22 havinga fil rn ofiirradiatedn resonant transformer, or g energy particle generators polyethylene laminated to the. top .andbbttom. urface 5 Of 50,000 t0 50,000,000 volts or a Van de Graaf elech flj fl i dic d b numeral .20 tron generaton. Infadditionto theme of electrons,

In FIGURE4, a three-quarter irlchflap 24- extends there eanlbe employedibeta'reys, g y -e, y from both faces of the envelope beyond the opening 34 employing cobalt 60, etc.

in the cardboard envelope 22, There can be employed any ofthe iradiation procedures In FIGURE 5, the record has-been. insertedonto the 10 disclosed in Colombian Patent 8.767 for example. fold or envelope 22 d h projecting.endsfz4 h The biaxial orientation is normally carried out to an been sealed at 26 and simultaneously cutso that the eXteIlt Of 100 110 700% longitudinally and 100 to 900% sealed and cut edge is about one-quarter inchfrom the: leterally- The biaxial Stretching can he carried out y cardboard; and blowing irradiated polyethylene tubing as disclosed in FIGURE 6 shows a stack .28 of'the record holde of the Colombian patent. The. irradiated, biaxially oriented FIGURE 5 and illustrates another advantage of the po y y p p y Such a Procedure base high invention. shrink energy, e.g. 100 to 500 p.s.i. at 96 C.

It is an acknowledged fact that rnanyirregular surfaced There can be p y as the Starting P y y products such as paint brushesflecord envelopes;as well fer the irradiation Procedure high, low medium assoft goods such as towels; pillows, candy bags,'heavy' yp y y P p y low of high'pressul'e techbulk materials like grain or flour, dry cleaners garment q The Starting polyethylene n h v a molecular bags, etc. when placed into conventional display wrap- Weight of 7,000 or 12,000 19100001 3 pings cannot be stacked on open shelves in quantity be- 00001 35, 0 e highercause of their tendency to slip and tumble. The pecufi Place of irradiated P y y there n be mliarly high interfacial friction of the instant irradiated 25 P y Similarly irradiated p p Py polyethylene film can be used to advantage to-overcome W t i claimed i this disadvantage of other wraps. A stack of slippable articles free of restraint, each of Thus in FIGURE 6, the stack 28 of the laminated said articles being packed in a film container or irradiated record holders will not tend to upset itself even though poly ylene, a i ad n being 0 an nt f all it-' may receive slight jars 'or vibrations while on. the 30 least 2 megarads, said 'film being laminated by an ad- 1 display shelves. hcsive to an inner cover for each of said articles, said' FIGURE 7 illustrates a single confectionery bar 30; inner cover being made of a cellulose material, the ten- Wrapped in irradiated polyethylene film in accordance deney 0f the articles to pbeing s b ta y reducedwith this invention. due to said container.

FIGURE 8 illustrates a stack 40 of confectionery bars illustrating, as does FIGURE 6, the advantages of 'stack- References Cited In the file of thls Patent inTlg'articles wrappedin accordance with this invention. UNITED STATES PATENTS e interfacial friction makes possible a steadier, more 7 Stable display of stacked articles. E332 The value of this particular stackingfeature is more 40 2643048 g 1953 a readily appreciated when it is realizcd'that in order to 2:801:446 Wohnski' Aug 1957 r m the dlsturbmg p e of u s y p y 2,877,500 Rainer et a1. Man 17, 1959, appllcatlon of relatively expenslve addltlves to the surfaces of the package Wrapping materials have been em-. FOREIGN PATENTS ddf h th d t f an 1,125,803 France July 16, 1956' ese a lives ave e lsa van age 0 occasion y leaving an undesired whitish deposit. OTHER REFERENCES In general, there is employed in the invention poly- 62 Chemical Engineering, pp. 228, 230, 232, 234,

ethylene film or tubing which has been irradiated to an eptember 1955. extent of 2 to megarads, prefcrablydto-ZO mega- 

